The invention relates to a valve device with a valve housing, through which passes a fluid passage, in which are formed a valve seat and a valve member accommodated so that it may be moved relative to the valve seat, with an electro-mechanical actuating means for moving the valve member between at least two functional positions in order to influence a cross-section of the fluid passage, and with a control device which is adapted to activate the actuating means on the basis of a control signal and which includes delay means which, in connection with a valve switch-off process, are adapted for delayed-action movement of the valve member into a switch-off position.
According to prior art, a valve device is known which is provided for use in process plant such a chemical or bio-reactors, or in machining centres such as lathes or milling centres. The known valve device is used to provide a fluid flow, in particular a compressed air flow, to a fluidic load, in particular an actuator, connected to the valve device. The fluid flow should also be maintained for a certain period of time after switch-off of a central controller such as for example a programmable control system adapted to control the valve device and the entire process plant or machining centre. Because of this pressurisation of the fluidic load beyond the actual period of use, it is possible to ensure for example a rinsing process for the fluidic load after switch-off of the process plant or machining centre. This rinsing process is used for example to prevent undesired penetration of cleaning fluids into areas of the fluidic load under fluid pressure. The known valve device includes for this purpose a pneumatic timer which is activated after switch-off of an electrical supply voltage provided to the valve device during regular operation and, after a presettable period of time has elapsed, ensures a purely pneumatic movement of the assigned valve member into a switch-off position.